1. Field of the Invention
The present invention is directed to integrating optics on the wafer level, particularly for realizing a high numerical aperture system.
2. Description of the Related Art
Magneto-optical heads are used to read current high-density magneto-optic media. In particular, a magnetic coil is used to apply a magnetic field to the media and light is then also delivered to the media to write to the media. The light is also used to read from the media in accordance with the altered characteristics of the media from the application of the magnetic field and light.
An example of such a configuration is shown in FIG. 1. In FIG. 1, an optical fiber 8 delivers light to the head. The head includes a slider block 10 which has an objective lens 12 mounted on a side thereof. A mirror 9, also mounted on the side of the slider block 10, directs light from the optical fiber 8 onto the objective lens 12. A magnetic coil 14, aligned with the lens 12, is also mounted on the side of the slider block 10. The head sits on top of an air bearing sandwich 16 which is between the head and the media 18. The slider block 10 allows the head to slide across the media 18 and read from or write to the media 18.
The height of the slider block 10 is limited, typically to between 500-1500 microns, and is desirably as small as possible. Therefore, the number of lenses which could be mounted on the slider block is also limited. Additionally, alignment of more than one lens on the slider block is difficult. Further, due to the small spot required, the optics or overall optical system of the head need to have a high numerical aperture, preferably greater than 0.6. This is difficult to achieve in a single objective lens due to the large sag associated therewith. The overall head is thus difficult to assemble and not readily suited to mass production.